Johnson claimed mistakes by former Trojans assistant strength and conditioning coach Jamie Yanchar contributed to him dropping 275 pounds of weight on his neck and crushing his voice box.
The terms of the settlement were kept confidential.
The suit stated that Yanchar was distracted and yelling at safeties Will Harris and Taylor Mays and not paying attention to Johnson at the time that the bar was being lifted from the weight rack. Yanchar bumped into the bar before Johnson had a chance to grip it with both hands, according to the suit.
But according to the USC court papers, Johnson signed a release shortly before the Sept. 28, 2009 accident, acknowledging the possibility of injury while taking part in athletics and agreeing not to sue USC if he was hurt.
Johnson eventually recovered from his injuries. He played two years with the Trojans and now plays in the NFL for the Washington Redskins.
City News Service contributed to this report.